FLEXIBLE PACKS 49 of coating. Saran-coated paper has been used on the Continent for shampoos but for thin liquids it was found to be not enough robust. It is, however, satisfactory for thick creams. Polyvinyl chloride Although not a new material in itself, several new grades of plasticised P.V.C. have recently come on to the market. These have lower melting points than the unplasticised grade, and should make handling far easier than it has been in the past on conventional heat sealing equipment. Polyamide Usually known as nylon, this material can be used as a film or can be extrusion coated on to paper or foil. This material has very good barrier properties for moisture vapour, grease, odour, and oxygen, although once again its melting point is rather high. This high melting point can be a virtue in that, like polypropylene, nylon can be used for steam sterilisation. When used alone it has to be impulse sealed, although it can be heat sealed by conventional means when it is the inside ply of a lamination. It is not possible to evaluate comprehensively all the materials which are available for packaging purposes, either as individual films or combined in two or three plies as laminations. When considering the packaging of any product, the following questions must be asked: 1. What material will give the required degree of protection against (a) gain or loss of moisture, (b) grease penetration, (c) oxygen penetration, (d) loss through absorption or penetration of essential ingredients scents, etc. (e) Will any ingredient in the product react with the material, due to plasticiser content, etc ? 2. Is the material capable of being printed economically to form an attractive container ? 3. Can the material be handled at commercial speeds on available machinery ? 4. Is the cost of the material such as to make the proposed combination commercially acceptable ? During recent years, a great number of combinations of materials have been tried, but only a few have been found to meet all the requirements outlined above. So far the following has been established:

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 1. For liquids containing detergents, i.e., shampoo, Pliofilm or P.V.C. are acceptable as the inner ply of a lamination. Polythene has not proved reliable owing to a tendency to weaken and delaminate over a period. Saran film, whilst providing very good protection, is extremely difficult to seal satisfactorily in film form, and when applied as an emulsion does not give a sufficiently strong seal to hold other than very viscous products. 2. The problem of packing powders or granular products does not present the same problems as, broadly speaking, these products have to be protected from access to moisture, oxygen, etc., from the outside, and the components of the lamination are rarely in contact with liquid, but have to stand up to conditions of high humidity. For this class of product a wide range of materials is available in the form of laminations of paper, aluminium foil, Pliofilm, polythene, Saran, P.V.C., and vinyl films, so that it is possible to tailor a material to suit the most exacting requirements. 3. Preparations containing large proportions of water do not present quite the same problems, although loss of essential ingredients through plastic film is always a matter which requires checking in each individual case. What of the future ? How far will the use of flexible packaging material extend into the cosmetic field ? Already it is making its presence felt with the single facial tissue which is impregnated, and contained in a sealed pouch. This type of toilet preparation was first used on airlines but it has now a much wider market. Face packs in sachet form have a steady sale, and combination packs of hair tints and shampoo have certainly arrived. The "one shot" pack although perhaps not economical from the con- sumers' point of view, is becoming more and more popular. Hand cream, face cream, or hair cream, packed in this way are certainly possibilities for the holiday trade or for travelling. On the Continent, catch-covers con- taining sachets of different sorts of beauty preparations are sold so that women can try small portions inexpensively and thus determine which they like best. This type of pack can also be used as the "give away" to introduce a new line. In all, although unlikely to greatly affect the field of beauty preparations which are catered for adequately by a wide variety of jars, bottles, tubes, etc., flexible packaging must surely play a much larger part in the market of cosmetics and toilet preparations in the future. (Received: 17th May 1961) REFERENCE •Christie, H.W. Modern Packaging. 34 213 (April) (1961).